碰到一个switch case疑惑

我有一个判空函数

func IsEmpty(val interface{}) bool {
    if val != nil {
        switch v := val.(type) {
        case bool:
            return false
        case string:
            return v == ""
        case int64, int8, int32, int, int16, float64, float32, uint64, uint8, uint32, uint, uint16:
            return v == 0
        case time.Time:
            return v.IsZero()
        case []interface{}:
            return len(v) == 0
        case []byte:
            return len(v) == 0
        case []int64:
            return len(v) == 0
        ....
        }

    }
    return true
}

case数组类型时，觉得代码很恶心

于是我像下面这样写

func IsEmpty(val interface{}) bool {
    if val != nil {
        switch v := val.(type) {
        case bool:
            return false
        case string:
            return v == ""
        case int64, int8, int32, int, int16, float64, float32, uint64, uint8, uint32, uint, uint16:
            return v == 0
        case time.Time:
            return v.IsZero()
        case []interface{}, []byte, []int64....:
            return len(v) == 0
        }

    }
    return true
}

但是代码报错了，len() 参数错误。

这个地方比较疑惑，求大佬解释一下，或者有什么更好的实现